Connecting parts such as pierce and clinch nuts and pierce form studs are used to fasten screws and bolts to parts made from steel plate or aluminum plate. The end faces of these connecting parts themselves may act like a punch piercing the steel or aluminum plate, and at the same time, the end face of each connecting part is sealed by the hole which it has punched out, and in this way the connecting part is fixed to the steel plate.
The popular method of driving connecting parts such as a pierce nuts into a steel plate is to supply pierce nuts between the top and bottom platens of a metal die set in a press machine, and drive the pierce nuts into the steel plate with a drive punch as the press ram is lowered.
The machine used to supply pierce nuts to the mold during this pierce nuts insertion process is a machine recorded as Japanese Patent Opening 1981-102437. This machine and the way it inserts pierce nuts are explained with reference to FIG. 11 of this application. The machine is composed of a magazine wound in a coil shape 1 and a pipe 2 linked by a metal clamp 4. The other end of the pipe 2 is connected to the mold by a metal clamp 6. The pierce nuts slide smoothly inside the magazine 1 and the pipe 2, and air pressure applied from the other end of magazine 1 transports the pierce nuts through magazine 1 and pipe 2 in the direction of metal clamp 6 and supplies them to the metal mold. The supply of pierce nuts to the metal mold is performed continuously, synchronized with the vertical motion of the press ram K.
When pierce nuts are transported in the magazine 10 by the pressure of compressed air commonly available in factories (5 to 6 kilograms per square centimeter), a maximum of 2,000 pierce nuts can be placed in the magazine 10. This means that when an existing pierce nut feeder is used, after every 2,000 shots, the press is stopped while the operator real aces the empty magazine with one filled with pierce nuts.
When, for example, pierce nuts are inserted on a transfer press equipped with metal molds for 10 processes, every minute, the press machine produces 40 products which have undergone the 10 processes, which means that the 2,000 pierce nuts in a single magazine are exhausted in 50 minutes. Therefore, every 50 minutes, the transfer press must be shut down and an operator has to stop his other work to quickly replace the empty magazine. Transfer presses, now larger, faster, and more expensive than in the past, must be shut off frequently, further reducing their operating rates.
This invention is intended to provide a continuous parts feeder that permits continuous transfer press operation by automatically switching from an empty magazine to a new magazine filled with parts. It is also intended to provide a continuous parts feeder that guarantees smooth parts transport when the magazines are switched over.